Why is email regex unreliable?

The full email specification (RFC 5321) allows characters and formats most regex patterns do not cover. Use regex for basic sanity checks but always send a confirmation email to verify deliverability.

Should I allow plus-addressing in emails?

Yes. Addresses like user+tag@example.com are valid and widely used for filtering. Make sure your regex includes + in the allowed characters before the @ sign.

How do I test my regex against multiple inputs?

Enter each test email on a separate line in the test string area. The tester highlights matches and non-matches so you can verify each case at a glance.

Regex Pattern for Email Validation

Email validation regex is one of the most commonly written and miswritten patterns in software. This example provides a practical pattern that accepts the vast majority of real email addresses while rejecting obvious invalid inputs. Test it against edge cases like subdomains, plus-addressing, and long TLDs. Remember that the only true email validation is sending a confirmation message.

Example

/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+.[a-zA-Z]{2,}$/

# Test cases (one per line):
[email protected]
[email protected]
invalid-email
missing@tld
@nodomain.com
[email protected]

[ open in Regex Tester → ]

FAQ

Why is email regex unreliable?: The full email specification (RFC 5321) allows characters and formats most regex patterns do not cover. Use regex for basic sanity checks but always send a confirmation email to verify deliverability.
Should I allow plus-addressing in emails?: Yes. Addresses like [email protected] are valid and widely used for filtering. Make sure your regex includes + in the allowed characters before the @ sign.
How do I test my regex against multiple inputs?: Enter each test email on a separate line in the test string area. The tester highlights matches and non-matches so you can verify each case at a glance.

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